Perl Style: Use $_ in Short Code

Contrary to beginners' belief, $_ improves legibility. Compare:

    while ($line = <>) {
        next if $line =~ /^#/;
        $line =~ s/left/right/g;
        $line =~ tr/A-Z/a-z/;
        print "$ARGV:";
        print $line;
    }

with:

    while ( <> ) {
        next if /^#/;
        s/left/right/g;
        tr/A-Z/a-z/;
        print "$ARGV:";
        print;
    }

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